Materials testing and characterization of four X60-X65 pipeline steels

Abstract

This report summarizes the main results from the slow strain rate tensile testing campaign performed within the framework of the HyLINE project. The base metals and weld simulated heat affected zones of four pipeline steels, in four different positions of the pipes, have been tested under in-situ electrochemically charged hydrogen conditions and in air as a reference. Metallurgical characterization and hardness testing has also been carried out. The two materials which showed the highest and lowest susceptibility to hydrogen embrittlement quantified through the Embrittlement Index (EI) have been the S-X65 and the T-X65 materials, respectively. The materials which revealed the highest and lowest susceptibility to hydrogen embrittlement, quantified through the Embrittlement Index (EI), were the S-X65 and the T-X65 materials, respectively. These two pipeline steels have been selected for further investigation in terms of fracture toughness and fatigue crack growth resistance both in air and in hydrogen charging conditions.